The invention relates to a layered composite with at least one decorative surface and comprising a backing layer made from a thermoplastic polymer which is not polypropylene, a decorative layer arranged thereupon and a heat-cured layer applied to the decorative layer. The present invention also relates to a process for producing this layered composite.
Layered composites of this generic type are known and essentially consist of a core material of wood or at least of wood-like material, such as wood-fiber material or separate layers of paper compressed with addition of resin, onto which decorative materials, such as woodgrains or marble effects combined with crosslinkable resin materials (overlays) are applied with exposure to heat and pressure. Materials of this type are described, for example, in the Euwid company brochure.
However, the known materials have the disadvantage of a certain sensitivity to moisture penetrating from the edges into the core layer, because the wood or wood-like material tends to swell when exposed to moisture. The compression of the composites is, moreover, an expensive process in relation both to the energy which it requires and to costs, since the compression has to be carried out at from 140 to 180° C. and at pressures of up to 200 N/cm2, and there is then also a post-press treatment lasting several days in order to prevent deformation of the sheets and form an ideally sealed surface.
For numerous industrial applications, for example in the automotive or electrical industry, there is a need for surface materials which on the one hand have high scratch resistance and on the other hand have relatively high heat resistance and which moreover can readily be provided with a decoration.
Surfacing material used for some time in furniture manufacturing has a number of layers, inter alia a backing layer, a decorative layer and a heat-cured layer lying thereupon, which with the aid of other bonding layers, for example made from paper or from adhesive films, produce a decorative layered composite. A layered composite of this type is, however, very complicated to produce, and often has a high formaldehyde content and exhibits undesirable swelling behavior.
The earlier Application DE-A 1 97 22 339 discloses a layered composite which comprises a backing layer made from polypropylene, a decorative layer arranged thereupon and a heat-cured layer applied to the decorative layer. However, for some applications there is a need for a layered composite which, instead of a backing layer made from polypropylene, has a backing layer made from another thermoplastic polymer, and therefore possesses somewhat different mechanical properties.